This invention relates to a closed container having a rupturable portion which allows fluid pressure buildup to be vented therefrom, and in particular to a battery container.
Rupture panels and disks have long been used as a means for enclosing and venting closed containers. Such panels and disks are constructed to burst or rupture when the pressure of a fluid within the container exceeds a predetermined level, and may define a portion of the exterior surface of the container. Previous rupture panels, however, are typically made of a thin, easily deflectable, foil-like material, and are not very rigid. Such previous rupture panels perform unsatisfactorily in certain applications which require protection of the item within the container from being crushed or otherwise damaged. One application in which high rigidity of the entire exterior container surface is desired is a battery pack for powering portable electronic equipment in the field. Such equipment, for example, a radio, and its power source may be carried on the person and is subjected to various hazards which may result in damage to the batteries were they not adequately protected. Protection of the batteries, which may be provided by a container having a highly rigid exterior surface, is not the only criterion for such applications, however.
The batteries may be of a type which comprise materials such as Lithium-Sulfur Dioxide (Lixe2x80x94SO2), which may violently explode and create a sudden and high increase in pressure within the container. A D-cell sized Lixe2x80x94SO2 battery of the type which may be disposed within a closed battery container is estimated to release as much as 40 cubic feet of gas in less than 0.2 seconds when it explodes; a pressure rise within the container as a result of such an explosion is thus very sharp and substantial. A means of rapidly venting the closed container in which such batteries are disposed is therefore necessary, else, the container, particularly if highly rigid, may shatter as a result of the explosion, and produce high velocity, loose fragments which may cause injury to the person carrying the container, or those nearby. If the venting means itself comprises a portion of the container itself, and is to provide a highly rigid exterior surface, its rupturing may itself produce undesirable high velocity, loose fragments. A means of providing a highly rigid closed container having a means for venting which does not produce loose fragments is highly desirable.
The present invention solves the problems exhibited by the prior art applications by providing a container having a highly rigid exterior and means for venting fluids therein which does not produce loose fragments. One embodiment of the inventive container comprises a highly rigid flat panel which provides an exterior container surface and which has a substantially H- or I-shaped groove formed therein. Analogizing the shape of this groove to the cross-section of an ordinary I-beam having a center web interconnecting opposed flanges, the panel, in response to a sufficient rise in pressure within the container, ruptures first along the xe2x80x9cwebxe2x80x9d of the groove, separating thereacross, By and proceeds to tear along the groove xe2x80x9cflangesxe2x80x9d in opposite directions from the xe2x80x9cwebxe2x80x9d. The panel is plastically deformable, and includes portions between the flanges, on opposite sides of the web, which open outwardly as the panel ruptures, creating the effect of xe2x80x9cdouble doorsxe2x80x9d which are hinged at the opposite ends of the groove flanges, where the panel material is plastically deformed, but still comprising a single piece. Thus, no loose fragments are formed during the venting of the closed container. The panel may be comprised of a material having a grain which is oriented in a direction parallel to the groove flanges; the grain thereby promoting the tearing of the panel material along the groove flanges. The opening provided by the double doors allows a high volume of gas to rapidly escape the container, and the panel ruptures without shattering, thereby eliminating the danger of injury resulting from the fragmentation of the container.
The present invention provides a closed battery container having walls defining an interior which is subjected to one of a first and a second pressure, the first pressure much lower than the second pressure. The closed container includes a highly rigid panel at least partially forming one of the container walls, the panel having an interior surface exposed to the interior of the container, and an opposite, exterior surface. One of the interior and exterior panel surfaces is provided with a groove having substantially parallel first and second groove segments, the first and second groove segments laterally spaced, and a third groove segment extending between and connected to the first and second groove segments. The panel has a first portion which lies on one side of the third groove segment, and a second portion which lies on the opposite side of the third groove segment, the first and second panel portions integrally connected across the third groove segment at the first container interior pressure, whereby the panel is in an unruptured state. The first and second panel portions are integrally disconnected across the third groove segment in response to the container interior being at the second container interior pressure, whereby the panel is in a ruptured state.
The present invention also provides a closed container having walls defining an interior which is subjected to one of a first and a second pressure, the first pressure much less than the second pressure. The closed container includes a highly rigid panel at least partially forming one of the container walls, the panel having an interior surface exposed to the interior of the container, and an opposite, exterior surface. The panel has an unruptured state at the first pressure, and the panel is urged into a ruptured state in response to an increase in interior pressure from the first pressure to the second pressure. The container also includes means for forming a pair of outwardly swinging doors in the panel as the panel is urged into its ruptured state, the doors open and attached to the panel in the ruptured state.
The present invention further provides a closed container having walls defining an interior which is subjected to one of a first and a second pressure, the first pressure much lower than the second pressure. The closed container includes a substantially rigid panel at least partially forming one, of the container walls, the panel having an interior surface exposed to the interior of the container, and an opposite, exterior surface. One of the interior and exterior panel surfaces is provided with a groove having first and second elongate groove segments which extend smoothly along their respective lengths, the first and second groove segments laterally spaced, and a third elongate groove segment extending between and connected to the first and second groove segments, the panel having a first portion which lies on one side of the third groove segment, and a second portion which lies on the opposite side of the third groove segment, the first and second panel portions integrally connected across the third groove segment, whereby the first and second panel portions become disconnected across the third groove segment in response to the container interior being at the second container interior pressure, whereby the panel is in a ruptured state.